1. Field of the Invention
The present invention relates to a storage device for storing data in multi-valued form, as well as to a data writing method.
2. Description of the Related Art
Storage apparatuses such as flash memories are capable of storing data of two bits or more per cell in multi-valued form. Illustratively, the storage apparatus disclosed by Japanese Patent Laid-Open No. 2008-299919 allows data of two bits to be written to each cell. When data of two bits or more is stored in each cell in multi-valued form, the storage capacity of the storage apparatus is doubled.